In the field of nonvolatile semiconductor memory devices, three-dimensionally stacked memories that can achieve high integration relatively without being constrained by the limitations of resolution in photolithography technology are drawing attention. Some three-dimensionally stacked memories have a configuration in which, for example, memory strings each of which includes a columnar channel body, a tunnel insulating layer, a charge storage layer, and a block insulating layer stacked so as to cover the side surface of the channel body, and a plurality of conductive layers intersecting with the channel body and provided at prescribed intervals in the stacking direction are two-dimensionally arranged in a matrix configuration.
To increase the cell current, a technology is proposed in which a layer made of silicon germanium is provided on the upper surface of the channel body.
Here, in such three-dimensionally stacked memories, a GIDL (gate induced drain leakage) current is used to perform the erasing of data. Therefore, to improve the efficiency of erasing data, it is desired to increase the GIDL current.